1. Field of the Invention
The present invention relates generally to portable machine tools and accessories therefor, and more particularly to a specially-configured hand drill and corresponding combination stand and guide to ensure material removal at a precise angle and to a precise depth.
2. Description of the Related Art
Upright floor or bench mounted drilling machines or drill presses have long solved the problem of accurately drilling a hole in an object, including perpendicular to a surface and to a certain depth. If a work piece or large object cannot be placed under a shop or workbench drill press, however, the only practical way to drill a hole is using a portable drill motor or hand drill. When using such a hand drill it is difficult to drill a perpendicular hole to a precise depth.
Although the archives of the Patent Office contain many issued patents attempting to solve this problem, very few are viable solutions in today""s marketplace. This is because, in part, household handymen are unwilling to pay more than perhaps ten percent of the price of a hand drill for an accessory to provide perpendicular drilling and depth control. The inventors listed below have attempted to overcome the above-identified problem with little success.
Other disadvantages associated with the prior art include that the proposed devices are too heavy and bulky and thus not truly portable (e.g. the Turner ""702 patent). In most other instances the prior art devices fail to include a sufficient bearing surface against which to place the object to be drilled, and fail to locate the bearing surface sufficiently proximate the hole to be drilled (e.g. the Converse ""822 and Miller ""022 patents). These and other disadvantages associated with the prior art are believed overcome by the present invention.
Accordingly, a primary object of the present invention is to provide a lightweight and inexpensive tooling accessory adaptable to conventional hand-held portable drill motors, to enable perpendicular holes of controlled depth to be reliably and repeatedly produced around the house, on surfaces which cannot conveniently or easily be transported to a drill press. Also an object of the invention is to provide a versatile accessory that can be used to assist in accurately drilling into large, e.g. wall, surfaces as well as small objects.
In accordance with the present invention, disclosed is a portable, combination stand and guide for use with a hand drill having a modified body. The combination stand and guide includes a substantially flat base plate having a central opening, and a vertical member arising out of and perpendicular to the perimeter of the base plate. The vertical member has a curved cross-section sized to slidably engage corresponding curved slots in the modified body of the hand drill. The vertical member preferably has a stop located a variable distance from the base plate, and has markings indicative of that distance. The stop prevents further than desired movement of the hand drill towards the base plate. The base plate and vertical member are of preferably of one piece and fabricated of injection molded plastic.
Using the combination stand and guide and modified hand drill, the user may engage the vertical member with the hand drill, and the base plate may be placed against a surface to be drilled. Alternatively, a small object to be drilled may be placed on the base plate. Then the hand drill is slidably moved towards the base plate until the stop is reached, facilitating drilling of a perpendicular hole of a controlled depth. Optionally at the top of the vertical member is a cover that when folded down serves as a convenient handle to hold the device up against a large surface when desired.
Still in accordance with the invention, alternatively the vertical member may have a slotted cross-section sized to slidably engage a corresponding protruding bracket fixedly mounted to the body of the conventional hand drill. Preferably, the protruding bracket is of a t-shaped cross section. The protruding bracket may be mounted to the top or the sides of the body of the conventional hand drill.
Further still in accordance with the invention, there is a kit to convert a conventional hand drill into one, along with a tooling accessory, offering the capability of producing perpendicular holes of controlled depth. The kit includes the base plate and vertical member as described above, and the protruding member attachable to the body of the conventional hand drill and sized to slidably engage the vertical member. Again, there is a stop located along the vertical member a variable distance away from the base plate and markings indicative of that distance.
Additionally disclosed herein are methods in accordance with the present invention. A method of accurately producing holes with a hand drill includes the steps of: providing a tooling accessory consisting of a base plate in combination with a perpendicular vertical member; attaching a protruding member to the body of a conventional hand drill; slidably engaging the protruding member with the vertical member; placing the base plate against a large surface to be drilled; and sliding the hand drill along the vertical member while drilling through an opening in the base plate into the object to be drilled. Preferably, the user adds the opening in the base plate the first time the tooling accessory is used. The method can also be used to accurately drill holes in small workpieces placed on top of the base plate. The method may further include the step of setting a stop along the vertical member to control the depth of drilling.
Alternatively described, a method of converting a conventional hand drill into a modified hand drill for use along with a tooling accessory for accurately producing holes includes the steps of: providing the tooling accessory described above including a stop; attaching a protruding member to the body of a conventional hand drill; slidably engaging the protruding member with the vertical member; and drilling an opening in the base plate the first time the tooling accessory is used. Then by placing the base plate against a large surface to be drilled, and sliding the hand drill along the vertical member while drilling through the opening in the base plate into the object to be drilled until the stop is reached, accurate holes can be hand drilled.
These and other advantages of the present invention will become evident from the appended drawings and detailed descriptions of the preferred embodiments which follow.